Hollow mattress and inflation control therefor



Oct. ll, 1955 H, J, RAND 2,719,935

HOLLOW MATTRESS AND INFLTION CONTROL THEREFOR Filed DeC. 16, 1950 2 Sheets-Sheet l IN V EN TOR.

Oct. 11, 1955 H. J. RAND HOLLOW MATTRESS AND INFLATION CONTROL THEREFOR Filed Dec. 16, 1950 2 Sheets-Sheet 2 INVENTOR. HENRY c7.' RAND BY /,%%M& @mw

United States Patent() HOLLOW MATTRESS AND INFLATION CONTROL THEREFOR Henry J. Rand, Bratenahl, Ohio, assignor to Air Mass, Inc., Bratenahl, Ohio, a corporation of Ohio Application December 16, 1950, Serial No. 201,085

10 Claims. (Cl. 5-348) This invention relates to improvements in a hollow mattress and inflation control therefor.

One of the objects of the present invention is to provide an air mattress with two sets of interdigitatingair cells running transversely and substantially the full width of the mattress, together with novel means for alternately' inating and deiiating rst the odd numberedcells and `then the even numbered cells.

Another object of the present invention is to provide a novel control whereby the movement of the two sets of air cells is held to a minimum so that such movement will be less noticed by the patient lying on the mattress.

Other objects and advantages of the present invention will be apparent from the accompanying drawings and description and the essential features will be set forth `along the line 3 3 of Fig. 1;

Fig. 4 is a View similar to Fig. 3 but showing the alternate set of cells inflated;

Fig. 5 is a sectional view enlarged taken along the line 5 5 of Fig. 1;

Fig. 6 is a fragmental sectional view similar to a portion of Fig. 5 but showing another manner of constructing the edge of the mattress;

Fig. 7 is a side elevational view greatly enlarged of the control mechanism shown diagrammatically in Figs. 1 and 2 and with certain portions shown in section to more clearly show the` construction thereof;

Fig. 8 is a transverse sectional view taken along the line 8 8 of Fig. 7;

Fig. 9 is a transverse sectional view taken along the line 9 9 of Fig. 7; while Fig. 10 is an electrical diagram for the pump motor.

My improved mattress is designed as a nursing aid for bedridden patients. It is especially helpful` for patients unable to` move and who would ordinarily require constant nursing attention such as frequent turning and back massage. These patients become uncomfortable and frequently develop bed sores due to pressure points which cut off circulation.

One form of my improved mattress is composed of forty-tive tubes or compartments of approximately ll/t inches in diameter extending from side to side of the mattress. The even numbered tubes or compartments are connected-together to form one set while the odd numbered `tubes or compartments are connected together to form another set. The sets of tubes are alternately intlated and deflated approximately every three to five minutes. This cycle is so slow that it is barely perceptible to the patient. The rhythmical changing of pres- Mv 2,719,985 ce Patented Oct. 11, 1955 sure points relaxes the patient and tends to induce sleep. However, the most important feature is that the pressure points under the body are being constantly changed.

As shown in Fig. 2, my improved mattress 10 is placed on top of an ordinary mattress 11 in its normal position on the bed 12. The bed is then made up as usual except that, since my improved mattress is waterproof, it does not need to be protected by a rubber sheet and is easily washed after each patients use thereof. The control apparatus shown at 13 may be positioned under the bed or in another inconspicuous place and connected by air tubes 14 and 15 with the two sets of mattress cells respectively.

Referring to Figs. l, 3, 4 and 5, a preferred form of my improved mattress is made of two thin sheets of a synthetic plastic which are sealed together along the full lines of Fig. l by the application of heat and pressure in a known manner. This provides an arrangement wherein the odd numbered cells C1, C3, C5 and so forth are connected in a single set communicating with the longitudinally extending passageway 16. In a similar manner, the even numbered cells C2, C4, Ce, are connected in a second set which communicate with the longi tudinally extending passage 17. Obviously, tube 14 provides control of the even numbered cells while tube 15 provides control of the odd numbered cells. e

I prefer to stiften the longer side edges of the mattress and one manner of doing so is shown in Figs. 3, 4 and 5 where coil springs 18 extend the full length of the mattress on opposite sides thereof, one of these coil springs being in the passageway 16 and the other in the passageway 17. Another manner of stiifening the longitudinal side edges is shown in Fig. 6 where the plastic material is gven a pluralty of folds as indicated at 19 extending the full length of the mattress, one along the passageway 16 and one along the passageway 17.

The mechanism in the control case is clearly shown in Fig. 7. An electric motor 20 supplied with a suitable source of current through the wires 21 and 21 is mounted on a base 22 and directly connected to a small air compressor 23. The base 22 is preferably mounted by shock reducing rubber cutis 24 on a partition plate 25 in the control box. The compressed air from the compressor 23 is led through a conduit 26 to a passageway 27 and an air inlet port 2S in a lixed control plate 29. This plate is mounted for movement horizontally on four bolts 30 which are rigidly supported on a bracket 31 which in turn is mounted on the partition plate 25. The bracket 31 also supports a small electric motor 32 with a self-driven fan 33 for cooling the apparatus. The driven shaft 34' of motor 32 has secured to it by a pin 35 the movable control plate 36, best seen in Fig. 9. Plate 36 is provided with a series of ports and passageways which coact with the ports of plate 29 which are clearly shown in Fig. 8, as plate 36 is rotated by the motor. A helical spring 3'7 coiled around shaft 34 acts in compression between the bracket 31 and the plate 29 so as to urge this plate toward the right as viewed in Fig. 7 lirmly against rotating plate 36. The nuts 30a' on bolts 30 are nicely adjusted so that plate 29 is firmly pressed against plate 36 but with insufficient friction to prevent proper operation.

Motor 20 is connected by lines 21 and 21 directly across fhe line L1, Lz as shown diagrammatically in Figure 10. It should be understood that when the cells Cr, C2 and so forth are inflated as shown in Figs. 3 and 4, there is a limit to the desirable pressure of such inflation. In one form of my device, this pressure is held to 1% to 11/2 pounds per square inch. In order to hold this pressure, I have shown means in Figs. 7 and l0 for stopping the motor 20 when the upper limit of pressure is reached. As shown in Fig. 7, va branch line 38 connected with line 26 leads the compressed air to a diaphragm chamber 39 in which is supported a flexible diaphragm 40 normally urged upwardly by means of a helical spring 41. An adjustable `screw 42 extends downwardly from a fitting 43 connected to the diaphragm and this engages against the actuator 44 of a micro-switch 45 which is normally closed as shown in full lines in Fig. l0, but which is movable to dot-dash position to open the motor circuit whenever the pressure in diaphragm chamber 39 is suicient to overcome spring 41.

The compressor 23 may be any small efficient compressor adapted to run most of the time. I prefer, however, to utilize my improved compressor as shown in my United States Patent No. 2,690,295, granted September 28, 1954.

Referring now to Figs. 7, 8 and 9. the control of pressure uid to the various cells of the improved mattress will be described. In Fig. 8, I have shown port 28 which is connected by passageway 27 with line 26 so that pressure fluid is always available at port 28. Port 46 in plate 29 leads through a passageway 47 in the plate to line 14, this connection not being shown in Fig. 7 as it would only confuse the drawing. Another port 48 diametrically opposite the port 46 leads through a passageway 49 in plate 29 to line 15, this connection not being shown on Fig. 7 as it would only confuse 'that drawing.

In Fig. 9 there are shown the ports and passageways in the movable distributor plate 36, these being .shown on that side of plate 36 which abuts plate 29 and cooperates with the ports just described. The annular passageway 50 which is a groove in plate 36 as clearly shown in Fig. 7, is positioned so it is always in communication with port 28 as clearly shown in Fig. 7. A radial groove passageway 51 leads outwardly to a passageway 52 which is a groove a little more than 180 in extent, being here shown as approximately 210. An exhaust passageway 53 arcuately in line with the groove passageway 52 communicates with a port 54 which extends entirely through plate 36 as shown in Fig. 7 and is tted with an exhaust pipe 55. The groove passageways 52 and 53 are so positioned that they coact with ports 46 and 48 in plate 29. While the exact arcuate extent of passageways 52 and 53 need not be just as I have shown them in Fig. 9, I have indicated there that passageway 53 encompasses an arc of about 60 While there is about a 45 gap between the ends of passageway 53 and the opposite ends of passageway 52.

With the ports in' the position of Fig. 7, and with motors 20 and 32 running, the operation of my improved control is as follows: With the plates of Figs. 8 and 9 superposed upon each other in the positions shown in the drawings7 passageway 52 will connect ports 46 and 48. Since the constantly rotating plate 36 has just reached this position, assuming that the odd numbered set of cells supplied by line 15 has just been deflated as shown in Fig. 4, passageway 52 will serve to conduct some of the pressure from line 14 and the even numbered cells to line 15 and the odd numbered cells so that for a short time the two sets of cells will become equalized in pressure. This period of time is represented by l to 30 degrees movement of plate 36. Thereafter, for a little more than l80 of travel of plate 36, air under pressure will be conducted from port 28 to port 48 through passageway 52 so as to fill up the odd numbered cells supplied by line to their` fully inated position as shown in Fig. 3. After plate 36 has traveled about 45 from the starting position assumed a few moments ago, the exhaust passageway 53 will coincide with port 46 and the remaining pressure fluid in the even numbered cells will then exhaust out port 54 and exhaust pipe 55. At this time the even numbered cells will soon have a pressure of approximately zero While the odd numbered cells will have between one-half and threequarters of their full pressure. After a little over 180 of rotation of plate 36 from the starting point, the position of the passageways as shown in Fig. 9 will be reversed from top to bottom. Again passageway 52 will connect ports V46 and 48. Just before this position is reached, the odd numbered cells will be at their full pressure and the even numbered cells will be substantially flat as shown in Fig. 3. When passageway 52 connects ports 46 and 48, the pressure will be equalized between the two sets of cells so that each of them becomes approximately half inflated. From this point, for about ports 28 and 46 will be connected through passageway 52 and the even numbered cells will be lled to full pressure through line 14. At the same time, after about 45 of movement from the point where the two sets of cells were equalized, passageway 53 will register with port 48 so as to exhaust the odd numbered cells to atmosphere. At this time the even numbered cells will have between one-half and three-quarters of their full pressure. As the parts approach their starting point as shown in the position of plates 36 and 29 in Figs. 9 and 8 respectively, just before passageway 52 again connects ports 46 and 48, the even numbered cells supplied through line 14 will have their full pressure and the odd numbered cells will be substantially flat as shown in Fig. 4.

l have thus disclosed a control system for two sets of interdigitating air cells whereby as odd numbered cells are inflated the even numbered cells are deflated and vice versa so as to change the pressure points on the patients body. At the same time I have conserved compressed air by utilizing the air stored in the fully inflated set of cells to half inflate the fully deflated set of cells. I have also limited the movement of the patients body at any one moment to approximately one-half of the movement between fully inflated and fully deated positions of the cells. When one set of cells is fully iniiated and the other set fully deflated, I only drop the fully inflated cells to half position. When one set of cells is only slightly more than half lled, I then drop the other set of cells to fully deflated position. I thus limit the movement of the patients body at all times.

It should be understood that the movements above described take place very slowly. The rotation of the distributor plate 36 is held to three or four revolutions per minute. The compressor 23 is of such capacity and driven at such a rate that it builds up the pressure very slowly in the set of cells which is being inflated. By means of the limit switch 45 I hold the top pressure in the fully inflated cells to a predetermined position of relatively low pressure.

What I claim is:

1. In combination with a mattress having a rst set of expandable cells and a second set of expandable cells, a source of uid pressure for inflating said cells, and a continuously moving distributor valve operatively connected between said source and said sets of cells, said valve having a pressure port communicating with said source and having rst and second ports communicating respectively with rst and second sets of said mattress cells, said valve having a distributor plate with passageways for connecting said ports and having an exhaust port leading to atmosphere, means for rotating said plate, and said plate being movable into positions where progressively said passageways connect said pressure port with said first port, said exhaust port communicates with said second port, said pasageways connect said irst and second ports with said pressure port, said passageways connect said pressure port with said second port, said exhaust port communicates with said rst port, and said passageways connect said rst and second ports with said pressure port.

2. In combination with a mattress having a first set of expandable cells and a second set of expandable cells, a source of fluid pressure for inflating said cells, and a continuously moving distributor valve operatively connected between said source and said sets of `cells, said valve having a base and a rotatableplate, said base and plate having mating flat surfaces, a shaft located centrally `of said plate and secured thereto, means -for rotating said shaft and plate, there being a pressure port in said base communicating with said source and positioned at a first radius from said shaft, there being two mattress control ports in` said base communicating respectively with first and second sets of said cells and positioned at a second radius from said shaft, said mattress control ports being spaced apart by an arc of approximately 180, all of said ports terminating at said flat surface, there being an annular groove in said plate at said first .radius opening toward the flat surface thereof, there being an arcuate groove in said plate at said second radius of at least 180 extent and opening toward the flat surface thereof, a passageway connecting said annular and arcuate grooves, and there being an exhaust port in said plate at said second radius and arcuately midway between the terminal ends of said arcuate groove, said exhaust port communicating between the flat surface of said plate and atmosphere.

3. In an organization comprising a hollow flexible pressure-tight mattress having a plurality of sets of interdigitating cells and a source of pressure fluid for inflating said cells and a conduit system connecting said mattress and source; the combination therewith of pressure fluid control means for inflating one set of said cells from said source and for deflating another set of said cells, and pressure fluid control means for thereafter providing fluid communication between said two named sets of cells and said source to provide for flow of pressure fluid from said source to said deflated set of cells.

4. The method of alternately inflating from a source of fluid pressure two sets of interdigitating cells in a hollow flexible pressure-tight mattress for supporting a patient, comprising the steps of inflating a first set of cells while deflating a second set of cells, of equalizing the pressure fluid between said first and second set of cells by the weight of said patient thereon, of inflating said second set of cells while deflating said first set of cells,

and of again equalizing the pressure fluid between said first and second set of cells by the weight of said patient thereon, wherein the steps of equalizing the pressure conserve the pressure fluid and minimize the movement of the supported patient of said cells.

5. In combination with a mattress having a first set of cells and a second set of cells, a source of fluid pressure, a first conduit connected to the first set of cells, a second conduit connected to the second set of cells, valve means connected to said conduits arranged to pass successively through a cycle of positions including a first position interconnecting said source and one of said conduits, while connecting the other conduit to atmosphere, said valve moving to a second position in which both conduits are interconnected and communicate with the source and the atmosphere is cut off, and a third position in which the other conduit is connected to the source while the one conduit communicates with the atmosphere, and means for effecting the cyclic operation of said valve.

6. In combination with a mattress adapted to support a human body thereon, said mattress having a first set of expandable cells and a second set of expandable cells, a source of fluid pressure, a first conduit connected to the first set of cells, a second conduit connected to the second set of cells, continuously moving valve means operatively connected to said conduits and arranged to continually repeat the cycle: (a) operatively connecting said source and said first conduit to inflate said first set of cells while exhausting said second conduit to deflate said second set of cells, operatively connecting together said conduits so that the weight of a body on said mattress cells equalizes the fluid pressure between said sets of cells with each cell expanded to only a fraction of its fully inflated size, operatively .connecting said source and said second conduit to inflate said second set of cells while exhausting said first conduit to deflate said first set of cells, and operatively connecting together said conduits so that the weight of a body on said mattress cells equalizes the fluid pressure between said sets of cells with each cell expanded approximately the same amount but only to a fraction of their fully inflated size.

7. In the combination, as set forth in claim 6, means for restricting flow from said source until after pressure equalization has occurred when said conduits are connected together.

8. In combination with a mattress having a first set of expandable cells and a second set of expandable cells, a source of fluid pressure for inflating said cells, and a continuously moving distributor valve operatively connected between said source and said sets of cells, said valve having a pressure port communicating with said source and having first and second ports communicating respectively with first and second sets of said mattress cells, said valve having a distributor plate with passageways for connecting said ports and having an exhaust port leading to atmosphere, means for rotating said plate, said plate being movable into positions where progressively said passageways connect said pressure port with said first port, said exhaust port communicates with said second port, said passageways connect said first and second ports so that any weight on said mattress will deflect the height of the cells therein and equalize the fluid pressure between each set of cells while supporting said weight with each deflected cell expanded to only a friction of its fully inflated height, said passageways connect said pressure port with said second port, said exhaust port communicates with said first port, and said passageways connect said first and second ports so that any weight on said mattress will deflect the height of the cells therein and equalize the fluid pressure between each set of cells while supporting said weight with each deflected cell expanded to only a fraction of its fully inflated height.

9. In an organization comprising a hollow flexible pressure-tight mattress having a plurality of sets of interdigitating cells and a source of pressure fluid for inflating said cells and a conduit system connecting said mattress and source; the combination therewith of pressure fluid control means for inflating one set of said cells from said source and for deflating another set of said cells, and pressure fluid control means for thereafter providing fluid communication between said two named sets of cells to provide for flow of pressure fluid from said inflated set of cells to said deflated set of cells so that any weight on said mattress will deflect the height of the cells therein and equalize the fluid pressure between each of said two named set of cells while supporting said weight with each deflected cell expanded to only a. fraction of its fully inflated height.

10. In an organization comprising a hollow flexible pressure-tight mattress having two sets of interdigitating cells and a source of pressure fluid for inflating said cells and a conduit system connecting said mattress and source; the combination therewith of a continuously moving distributor valve in said conduit system, said valve having ports and passageways arranged to continuously repeat the cycle: (a) inflate a first set of cells while deflating a second set of cells, (b) equalize the pressure fluid between said first and second sets of cells, (c) inflate said second set of cells while deflating said first set of cells, and (d) equalize the pressure fluid between said first and second set of cells, said source of pressure fluid `being a fluid compressor, an electric motor driving said compressor, an electric circuit energizing said motor and including a normally closed switch, a pressure responsive device operatively connected with said switch for opening the latter responsive to a predetermined pressure in said device, and a conduit communicating between said device and a point `in said conduit system between said source and valve.

References Cited in the file of this patent 8 Shurtliff July 20, 1915 Hart Aug. 5, 1930 Craig Aug. 25,y 1931 Hawley Oct. 18, 1932 Dalton Apr. 5, 1938 Rosett Mar. 28, 1944 

